diff --git a/bsd/sys/buf_internal.h b/bsd/sys/buf_internal.h
index 5319f03e9..29e63ee06 100644
--- a/bsd/sys/buf_internal.h
+++ b/bsd/sys/buf_internal.h
@@ -126,6 +126,7 @@ struct buf {
 	TAILQ_ENTRY(buf)        b_act;  /* Device driver queue when active */
 	void *  b_drvdata;              /* Device driver private use */
 	void *  b_fsprivate;            /* filesystem private use */
+	void    (*b_fsprivate_done)(void *);   /* callback for fs to cleanup its data. */
 	void *  b_transaction;          /* journal private use */
 	int     b_dirtyoff;             /* Offset in buffer of dirty region. */
 	int     b_dirtyend;             /* Offset of end of dirty region. */
diff --git a/bsd/vfs/vfs_bio.c b/bsd/vfs/vfs_bio.c
index 1c1318840..8c21b1d21 100644
--- a/bsd/vfs/vfs_bio.c
+++ b/bsd/vfs/vfs_bio.c
@@ -1113,10 +1113,14 @@ buf_fsprivate(buf_t bp)
 	return bp->b_fsprivate;
 }
 
+// if NULL callback is passed, it's ignored
 void
-buf_setfsprivate(buf_t bp, void *fsprivate)
+buf_setfsprivate(buf_t bp, void *fsprivate, (*release_callback)(void *))
 {
 	bp->b_fsprivate = fsprivate;
+	if (release_callback != NULL){
+		bp->b_fsprivate_done = release_callback;
+	}
 }
 
 kauth_cred_t
@@ -3921,6 +3925,10 @@ bcleanbuf(buf_t bp, boolean_t discard)
 		bp->b_bufsize = 0;
 		bp->b_datap = (uintptr_t)NULL;
 		bp->b_upl = (void *)NULL;
+		/* call fs callback to release private data */
+		if (bp->b_fsprivate_done != NULL){
+			(void)b_fsprivate_done(bp->b_fsprivate);
+		}
 		bp->b_fsprivate = (void *)NULL;
 		/*
 		 * preserve the state of whether this buffer
@@ -4493,6 +4501,7 @@ alloc_io_buf(vnode_t vp, int priv)
 	bp->b_bufsize = 0;
 	bp->b_upl = NULL;
 	bp->b_fsprivate = (void *)NULL;
+	bp->b_fsprivate_done = NULL;
 	bp->b_vp = vp;
 	bzero(&bp->b_attr, sizeof(struct bufattr));
 
diff --git a/tools/lldbmacros/memory.py b/tools/lldbmacros/memory.py
index 58d2f4f04..d2b7ad36e 100755
--- a/tools/lldbmacros/memory.py
+++ b/tools/lldbmacros/memory.py
@@ -4151,7 +4151,7 @@ def _GetBufSummary(buf):
         buf.b_flags, buf.b_lflags, buf.b_error, buf.b_bufsize, buf.b_bcount, buf.b_resid,
         buf.b_dev, buf.b_datap, buf.b_lblkno, buf.b_blkno, buf.b_iodone, buf.b_vp,
         buf.b_rcred, buf.b_wcred, buf.b_upl, buf.b_real_bp, buf.b_act, buf.b_drvdata,
-        buf.b_fsprivate, buf.b_transaction, buf.b_dirtyoff, buf.b_dirtyend, buf.b_validoff,
+        buf.b_fsprivate, buf.b_fsprivate_done, buf.b_transaction, buf.b_dirtyoff, buf.b_dirtyend, buf.b_validoff,
         buf.b_validend, buf.b_redundancy_flags, buf.b_proc, buf.b_attr]
 
     # Join an (already decent) string representation of each field